WO2012036500A9 - Novel electrode active material and lithium secondary battery comprising same - Google Patents

Abstract

The present invention relates to an electrode active material for a lithium secondary battery, comprising one or more compounds selected from the following chemical formula 1, and to a lithium ion battery comprising the electrode active material. Formula 1: Li_xMo_4-yM_yO_6-zA_z (1), where 0≤x≤2, 0≤y≤0.5, 0≤z≤0.5, and M is a metal or transition metal cation having an oxidation number of +2 to +4, and A is a negative monovalent or negative divalent anion.

Description

 Novel electrode active material and lithium secondary battery comprising same

 The present invention relates to a novel electrode active material and a lithium secondary battery comprising the same, and more particularly, there is little structural change in the repeated detachment and insertion of Li cations during charging and discharging, and a novel structural failure does not occur during overcharging. An electrode active material having a structure and a lithium secondary battery including the same.

 As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is increasing rapidly. Recently, the use of secondary batteries as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs) has been realized. It is becoming. Accordingly, many studies have been conducted on secondary batteries capable of meeting various needs, and in particular, there is a high demand for lithium secondary batteries having high energy density, high discharge voltage, and output stability.

 In particular, lithium secondary batteries used in electric vehicles have high energy density and high power output in a short time, and must be used for more than 10 years under severe conditions in which charging and discharging by a large current is repeated in a short time. It is inevitably required to have superior safety and long life characteristics than small lithium secondary batteries.

 In recent years, research has been actively conducted to use a lithium secondary battery in a power storage device that converts unused power into physical or chemical energy and stores it as an electric energy when needed.

 Lithium secondary batteries used in large-capacity power storage devices have to have high energy density and efficiency and have a long lifespan.In addition, fire and explosion accidents are linked to large-scale accidents when the system malfunctions due to high performance and large capacity, thereby ensuring safety and reliability. Is a particularly important task.

 In this regard, the conventional lithium ion secondary battery uses a lithium cobalt composite oxide having a layered structure for the positive electrode and a graphite-based material for the negative electrode, but in the case of lithium cobalt composite oxide, cobalt is a main component Is very expensive and is not suitable for electric vehicles or large capacity power storage devices in terms of safety.

 In addition, in the case of lithium manganese composite oxide, there is a problem in that manganese is eluted into the electrolyte due to the influence of the electrolyte during high temperature and high current charge and discharge, thereby degrading battery characteristics, and the capacity per unit weight compared to lithium cobalt composite oxide or lithium nickel composite oxide. This is small and there is a limit to the increase in capacity per weight. Therefore, much research has been conducted on active materials containing other elements.

 For example, Korean Patent Application Publication No. 2004-0092245 discloses a composition formula Li._{1 + x}[Ni (_{1/2 + a}) Mn (_{3 / 2-2a}Mo_a] O₄After preparing a spherical precursor powder having a particle size of 1 to 5 μm having a particle size of (0 ≦ x ≦ 0.1, 0 ≦ a ≦ 0.1), it was calcined at 700 ° C. to 1,100 ° C. to start a 5 Ｖ class positive electrode active material for a spinel structure lithium secondary battery. Doing. In addition, Korean Patent Application Publication No. 2010-0032395 discloses Li_pN_xM_yO_zF_a (Wherein N is at least one element selected from the group consisting of Co, Mn and Ni, and M is at least one kind selected from the group consisting of transition metal elements other than N, Al, Sn and alkaline earth metal elements) Element, wherein 0.9 ≤ p ≤ 1.3, 0.9 ≤ x ≤ 2.0, 0 ≤ y ≤ 0.1, 1.9 ≤ z ≤ 4.2, 0 ≤ a ≤ 0.05), the positive electrode active material of the lithium ion secondary battery having a perovskite structure Surface modified lithium-containing composite oxides are disclosed. However, they are lithium ions (Li⁺There is still a disadvantage in that there is a limit in securing structural safety due to repeated detachment and insertion of the c).

 In addition, researches to secure the safety of the positive electrode active material are continuing, but until now, the composition of a positive electrode active material and a lithium secondary battery including the same that have a reliable level of safety of medium and large lithium secondary batteries have not been proposed.

 Accordingly, an object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

 After in-depth research and various experiments, the inventors of the present application developed a lithium transition metal oxide for an electrode active material having a new composition and crystal structure. There was almost no change and structural collapse did not occur even during overcharging, and it was confirmed that the risk of ignition and explosion of the lithium secondary battery was significantly reduced, and thus the present invention was completed.

 Specifically, an object of the present invention is to provide an electrode active material having a structure in which lithium ions are firmly bonded to a centrally bonded oxide and do not interfere with detachment and insertion of lithium ions during charge and discharge.

 Therefore, the electrode active material for a lithium secondary battery according to the present invention for achieving the above object is characterized in that it comprises at least one compound selected from the formula (1).

Li _x Mo _4-y M _y O _6-z A _z (1)

 Where

 0 ≦ x ≦ 2;

 0 ≦ y ≦ 0.5;

 0 ≦ z ≦ 0.5;

 M is a metal cation having an oxidation number of +2 to +4;

 A is a -1 or -divalent anion.

 The compound may be used for a positive electrode or a negative electrode of a lithium secondary battery, but is preferably used as a positive electrode active material in order to solve the problems.

 In relation to the compound of Formula 1, its crystal structure is schematically illustrated in FIG. 1.

Referring to FIG. 1, the compound of Chemical Formula 1 is a bond between molybdenum (Mo)-molybdenum '(Mo') and oxygen (O)-in a direction in which Mo ₄ O ₆ is stacked and penetrated into the ground (paper surface). It has a structure in which an infinite chain between molybdenum (Mo) and oxygen (O) is formed. The infinite chains are arranged parallel to another infinite chain and are cross-linked with an oxygen (O) bridge to form an open channel where lithium ions are located.

 That is, since lithium ions are positioned in the center of the oxide of the tunnel structure that is firmly bonded to each other by the bond between Mo-Mo 'and O-Mo-O, there is no overall interference on the detachment and insertion of the lithium ions during charge and discharge. . Here, the 'tunnel structure' means a hollow structure that can be easily ion exchanged and inserted.

Therefore, even after repeated charging and discharging, the structure of the oxide remains stable regardless of the movement of lithium ions, which is completely different from the lithium transition metal oxides having a layered structure such as LiCoO ₂ and LiNiO ₂ .

Meanwhile, the overcharge state refers to a state in which lithium ions are excessively released from the positive electrode active material during charging. The overcharge state battery is a high temperature when O ₂ is taking place the reaction in which the glass (遊離) in the crystal in the temperature of the battery because it is determined collapsed by the reaction heat generated is more elevated, so that O ₂ is again A vicious cycle is released.

 On the other hand, the compound of the formula (1) constituting the electrode active material of the present invention, structural collapse does not occur even in the state of charge corresponding to the overcharge state in the conventional positive electrode active material. Therefore, electric vehicles or large-capacity power storage devices that require high energy density and efficiency, have a long life, and require a fairly high level of safety and reliability against fire or explosion when a system malfunctions due to high performance and capacity. It is suitable for use in lithium secondary batteries.

 In this regard, referring to Formula 1, the x value may be determined within a range of 0 ≦ x ≦ 2, and more preferably in a range of 0 ≦ x ≦ 1.

Li _x Mo _4-y M _y O _6-z A _z is prepared by replacing In or Na with Li in InMo _4-y M _y O _6-z A _z or NaMo _4-y M _y O _6-z A _z do. InMo _4-y M _y O _6-z A _z or NaMo _4-y M _y O _6-z A _z , In and Na are located in the center of the hole, but Li is smaller in size and may also be present in other locations in the hole. . Mixing with LiI during the manufacturing process may be present in a thermodynamically stable position by applying heat at 460 ℃ for more than 12 hours, it was confirmed that the element was replaced by x = 1.72 in the analysis. In addition, it was confirmed that x = 2 can be thermodynamically determined through computational chemistry, and the distance between Li-O is 2.0 kW, which is a reliable level. However, in the case of insertion / detachment electrochemically, the range where x is 1 or less is preferable because Li is located at the center of the hole, which is a position where diffusion is likely to occur, rather than being at a position where thermodynamic stabilization is performed.

In the case of x = 0, it is Mo _4-y M _y O _6-z A _z in which lithium ions are not present in the positive electrode. This full charge state corresponds to an overcharge state in a conventional positive electrode active material.

In the case of LiCoO _{2 having} a layered structure that is commonly used as a positive electrode active material, when the lithium ions of the positive electrode move to the negative electrode during charging, the LiCoO ₂ structure is collapsed. Thus, the layered structure capable of reversible insertion and desorption of lithium ions CoO ₂ may not be present.

On the other hand, since the compound of the present invention maintains a stable tunnel structure even in Mo _4-y M _y O _6-z A _z where lithium ions are not present at all, there is no structural change of oxide regardless of the movement of lithium ions. The structural collapse does not occur even in the previous state, that is, the overcharge state in the conventional cathode active material.

On the other hand, when x = 1, LiMo _4-y M _y O _6-z A _z is a state in which lithium ions are filled in crystal structure. In the lithium secondary battery, since lithium ions of the positive electrode are charged while moving to the negative electrode, and lithium ions of the negative electrode are discharged while moving to the positive electrode, x = 1 means a substantial portion of the discharge state.

 Therefore, in this case, since a large amount of lithium ions can all move to the cathode, high charging efficiency can be exhibited.

In addition, a part of Mo in Chemical Formula 1 may be substituted with another metal (M) element of + 2-valent to + 4-valent oxidation number. Therefore, Formula 1 may be represented by Li _x Mo ₄ O _6-z A _z when y = 0, and may be represented by Li _x Mo _3.5 M _0.5 O _6-z A _z when y = 0.5. .

 The transition metal (M) is preferably at least one selected from the group consisting of W, Nb, V, Al, Mg, Ti, Co, Ni and Mn, in this case, the preferred amount of substitution may be 0 <y ≤ 0.5 have.

 In addition, the oxygen ion in the formula (1) can be substituted with an anion (A) of the oxidation number -1 or -divalent in a predetermined range, the anion (A) is preferably F, Cl, Br, I, etc. It may be one or more selected from the group consisting of halogen, S and N. By the substitution of these anions, the bonding strength with the transition metal is excellent and the structural transition of the compound is prevented, so that the life of the battery can be improved. On the other hand, if the amount of substitution of the anion (A) is too large (z> 0.5), it is not preferable because the oxide does not maintain a stable tunnel structure and the lifespan characteristics are lowered.

 Method for producing the compound of Formula 1 is not particularly limited, one example will be described below.

First, M'Mo ₄ O ₆ was synthesized for 3 to 5 days at a temperature of 850 to 950 ° C. using a metal (M ′), molybdenum (Mo), and molybdenum oxide (MoO _x ) satisfying the stoichiometric ratio. The result obtained above may be prepared by reacting lithium iodide (LiI) with Li for 10 to 14 hours at a temperature of 400 to 500 ° C.

In this method, the metal (M ′) can be for example sodium (Na) or indium (In), and the molybdenum oxide (MoO _x ) is a MoO ₂ having an x value of x = ₂ or a MoO _{3 having} x = 3. Can be. The reason why the molybdenum oxide (MoO _x ) and molybdenum (Mo) are simultaneously added is to match the oxidation number of Mo.

In the electrode active material Li _x Mo ₄ O ₆ (0 ≦ _x ≦ 2), when Mo is replaced with a transition metal (M) or oxygen (O) is substituted with a halogen or the like, the compound is added before the high temperature reaction. Can be prepared.

 In some cases, when the electrode active material of the present invention is used for the positive electrode, in addition to the compound of Formula 1, other lithium-containing transition metal oxide, lithium iron phosphate may be further included.

Examples of the other lithium-containing transition metal oxides include layered compounds such as lithium cobalt oxide (LiCoO ₂ ) and lithium nickel oxide (LiNiO ₂ ), or compounds substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + y} Mn _2-y O ₄ (where y is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ and the like; Ni-site-type lithium nickel oxide represented by the formula LiNi _1-y M _y O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y = 0.01 to 0.3; Formula LiMn _2-y M _y O ₂ , wherein M = Co, Ni, Fe, Cr, Zn or Ta and y = 0.01 to 0.1, or Li ₂ Mn ₃ MO ₈ , where M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like, but are not limited to these.

Examples of the lithium iron phosphate include Li _{1 + a} Fe _1-x M _x (PO _4-b ) X _{b having an} olivine crystal structure, wherein M = Al, Mg, Ni, Co, Mn, Ti, Ga At least one selected from among Cu, V, Nb, Zr, Ce, In, Zn, and Y, and at least one selected from X = F, S, and N, -0.5≤a≤ + 0.5, and 0≤x≤0.5 , 0 ≦ b ≦ 0.1) and the like, but are not limited thereto.

 In this case, the compound of Formula 1 may preferably be 50% by weight or more based on the total weight of the positive electrode active material.

 The present invention also provides an electrode for a lithium secondary battery in which the electrode active material as described above is applied to a current collector. Looking at the specific manufacturing method of the positive electrode of the electrode including the electrode active material according to the present invention as follows.

 First, a paste is prepared by adding and stirring the electrode active material of the present invention, and a binder and a conductive agent in an amount of 1 to 20% by weight with respect to the electrode active material, respectively, and then applying it to a metal plate for current collector and compressing the paste. After drying, a laminate electrode can be prepared.

 The positive electrode current collector is generally made to a thickness of 3 μm to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver, or the like can be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

 Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), cellulose, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose Roses, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers, and the like. .

 The conductive agent is not particularly limited as long as it has conductivity without causing chemical change in the battery. Examples of the conductive agent include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used. Specific examples of commercially available conducting agents include acetylene black Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, Ketjenblack, EC series (Armak Company), Vulcan XC-72 (Cabot Company), and Super P (Timcal).

 In some cases, a filler may be optionally added as a component that suppresses the expansion of the positive electrode. Such a filler is not particularly limited as long as it is a fibrous material without causing chemical change in the battery. Examples of the filler include olefinic polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.

 As the dispersion, isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, and the like may be typically used.

 The method of evenly applying the paste of the electrode material to the metal material can be selected from known methods or performed by a new suitable method in consideration of the properties of the material. For example, it is preferable to disperse the paste onto the current collector and then to disperse the paste uniformly using a doctor blade or the like. In some cases, a method of distributing and dispersing in one process may be used. In addition, a method such as die casting, comma coating, screen printing, or the like may be used, or the current collector may be formed on a separate substrate and then pressed or laminated. It can also be bonded with.

 Drying of the paste applied on the metal plate is preferably dried for 1 to 3 days in a vacuum oven at 50 to 200 ℃.

 In another aspect, the present invention provides a lithium secondary battery comprising an electrode assembly and a lithium salt-containing non-aqueous electrolyte facing the negative electrode with the positive electrode interposed therebetween.

 For example, the negative electrode may be manufactured by coating and drying a negative electrode active material on a negative electrode current collector, and optionally further include components such as a conductive agent, a binder, and a filler as described above.

 The negative electrode current collector is generally made to a thickness of 3 to 500 ㎛. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like, aluminum-cadmium alloy, and the like can be used. In addition, like the positive electrode current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The negative electrode active material may be, for example, carbon such as hardly graphitized carbon or graphite carbon; Li _x Fe ₂ O ₃ (0 ≦ _x ≦ 1), Li _x WO ₂ (0 ≦ _x ≦ 1), Sn _x Me _1-x Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me' Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 <x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , Metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separator is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally from 0.01 to 10 ㎛ ㎛, thickness is generally 5 ~ 300 ㎛. As such a separator, for example, olefin polymers such as chemical resistance and hydrophobic polypropylene; Sheet or nonwoven fabric made of glass fiber or polyethylene; Kraft paper or the like is used. Typical examples currently on the market include Celgard series (Celgard ^R 2400, 2300 (manufactured by Hoechest Celanese Corp.), polypropylene separator (manufactured by Ube Industries Ltd. or Pall RAI), polyethylene series (Tonen or Entek), etc.).

 In some cases, a gel polymer electrolyte may be coated on the separator to increase battery stability. Representative examples of such gel polymers include polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, and the like.

 When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

 The said lithium salt containing non-aqueous electrolyte consists of a nonaqueous electrolyte and lithium. As the nonaqueous electrolyte, a nonaqueous electrolyte, a solid electrolyte, an inorganic solid electrolyte, and the like are used.

 As said non-aqueous electrolyte, N-methyl- 2-pyrrolidinone, a propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, for example , Gamma-butylo lactone, 1,2-dimethoxy ethane, 1,2-diethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, 4-methyl-1,3-dioxene, diethyl ether, formamide, dimethylformamide, dioxolon, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxy methane, dioxolon Aprotic organic solvents such as derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyroionate and ethyl propionate can be used. Can be.

 Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyedgetion lysine, polyester sulfides, polyvinyl alcohols, polyvinylidene fluorides, Polymers containing ionic dissociating groups and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, sulfates and the like of Li, such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , and the like, may be used.

The lithium salt is a good material to be dissolved in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, LiSCN, LiC (CF 3 SO 2) 3, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, 4 phenyl lithium borate, imide and the like can be used.

 In addition, in the electrolyte solution, for the purpose of improving the charge and discharge characteristics, flame retardancy, etc., for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, nitro Benzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride and the like may be added. . In some cases, in order to impart nonflammability, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further included, and in order to improve high temperature storage characteristics, a carbon dioxide gas may be further included, and fluoro-ethylene carbonate), propene sultone (PRS), and fluoro-propylene carbonate (FPC).

 The secondary battery according to the present invention has excellent life characteristics and safety, as can be seen in the following examples, experimental examples, and the like, and therefore, the secondary battery may be preferably used as a component battery of a medium and large battery module. Accordingly, the present invention also provides a medium-large battery module including the secondary battery as a unit cell.

 Such medium and large battery modules can be preferably applied to a power source that requires high output and large capacity, such as an electric vehicle and a hybrid electric vehicle, and can be applied to a large capacity power storage device in which stability and reliability according to high output and large capacity are important. .

 Since the construction of the medium-large battery module and its manufacturing method are well known in the art, a description thereof will be omitted.

1 is a schematic of a LiMo ₄ O ₆ crystal structure;

 2 is a graph showing the results according to Experimental Example 2;

 3 is a graph showing the results according to Experimental Example 3;

 4 is a graph showing the results according to Experimental Example 4;

 5 is a graph showing the results according to Experimental Example 5.

 Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

<Example 1>

In, MoO ₃ and Mo were put in a silica tube at a stoichiometric ratio and sealed under vacuum. The tube was synthesized in an electric furnace at a temperature of 895 ° C. for 4 days, and the synthesis product and lithium iodide (LiI) were put back into a silica tube and sealed in a vacuum state, and reacted at a temperature of 460 ° C. for 12 hours to form lithium molybdenum. Oxides were prepared.

 The lithium molybdenum oxide as a positive electrode active material, KS 6 as a conductive agent and KF 1100 as a binder were mixed in an 8: 1: 1 ratio (weight ratio), stirred with a solvent of NMP, and then coated on an aluminum foil as a metal current collector. . This was dried in a vacuum oven at 120 ° C. for 2 hours or more to prepare a positive electrode.

 The anode, the porous separator of Li metal, and polypropylene as the cathode and LiPF of 1 M₆A coin-type battery was manufactured using an electrolyte solution of an ethylene carbonate (EC) and dimethyl carbonate (DMC) solution having a salt ratio of 1: 1.

Comparative Example 1

A lithium secondary battery was manufactured in the same manner as in Example 1, except that a cathode active material was manufactured using LiCoO ₂ instead of lithium molybdenum oxide.

Experimental Example 1

 The lithium secondary batteries manufactured in Example 1 and Comparative Example 1 were measured for life characteristics while charging and discharging in a 2.0 to 4.2V region. The results are shown in Table 1 below.

TABLE 1

As shown in Table 1, the compound according to the present invention, although the capacity itself is less than LiCoO ₂ , when using it as a positive electrode active material, it can be seen that the actual capacity almost comparable to the theoretical capacity, and the average voltage It is very high as 3.4V.

Experimental Example 2

 X-ray diffraction (XRD) was performed on the lithium molybdenum oxide prepared in Example 1.

 XRD data were obtained at room temperature using a Bragg-Brentano diffractometer (Bruker-AXS D4 Endeavor) equipped with a Cu X-ray tube and Lynxeye detector in an angle range of 10 ° ≤2θ≤70 ° in 0.025 ° increments. . Such X-ray diffraction data was performed Rietveld refinement using the TOPAS program, the results are shown in FIG.

 It can be seen from the characteristic peaks of FIG. 2 that lithium molybdenum oxide was produced.

Experimental Example 3

 In Example 1, the reaction was reacted with LiI at 460 ° C. for 12 hours, and the reaction was repeated continuously. At this time, the Li content in the synthesized material was measured by ICP-AES (Perkin-Elmer). As a result, it was confirmed that Li is substituted up to 1.72 compared to Mo. When calculated to the state that Li is 2 compared to Mo through the calculation chemistry, Li-O distance is 2.0 Å reliable level, Figure 3 is a schematic of the crystal structure of the state.

Experimental Example 4

 The coin cells prepared in Example 1 were evaluated for electrical properties of the positive electrode active material using an electrochemical analyzer (VSP, Bio-Logic-Science Instruments). Using cyclic voltammetry (CV), experiments were performed at a rate of 0.5 mV / s in the 2.0 to 4.0V range. This result is shown in FIG.

 As shown in FIG. 4, it can be seen that Li ions are reversibly inserted and desorbed into the lithium molybdenum oxide according to the present invention.

 Experimental Example 5

 The coin cells prepared in Example 1 were evaluated for the positive electrode active material electrical characteristics using an electrochemical analyzer (VSP, Bio-Logic-Science Instruments). In the charge-discharge mode (charge-discharge mode) was experimented in the 2.0 ~ 4.2V region, the results are shown in FIG.

 As shown in FIG. 5, the capacity of the secondary battery using lithium molybdenum oxide according to the present invention as the cathode active material is 55 mAh / g, which is about 98% of the theoretical capacity, and the average voltage is 3.4V. In addition, since the charge and discharge graph has a linearity, the SOC state can be easily confirmed through OCV.

 As described above, the lithium secondary battery using the electrode active material according to the present invention has almost no structural change in oxide even after repeated charging and discharging, and there is no structural collapse during overcharging, thereby ensuring safety, thereby ensuring a safety power source or a large-capacity power storage device of an electric vehicle. There is an effect that can be used.

 Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (9)

1.  An electrode active material for a lithium secondary battery comprising at least one compound selected from Chemical Formula 1 below:

   Li _x Mo _4-y M _y O _6-z A _z (1)

    Where

    0 ≦ x ≦ 2;

    0 ≦ y ≦ 0.5;

    0 ≦ z ≦ 0.5;

    M is a metal cation in which +2 to +4 have oxidation numbers;

    A is a -1 or -divalent anion.
2.  The electrode active material according to claim 1, wherein the electrode is a positive electrode.
3.  The electrode active material of claim 1, wherein x is in a range of 0 ≦ x ≦ 1.
4.  The electrode active material of claim 1, wherein M is at least one selected from the group consisting of W, Nb, V, Al, Mg, Ti, Co, Ni, and Mn.
5.  The electrode active material of claim 1, wherein A is at least one selected from the group consisting of halogen, S, and N.
6.  The electrode active material of Claim 1 is apply | coated to the electrical power collector, The lithium secondary battery electrode characterized by the above-mentioned.
7.  A lithium secondary battery comprising the electrode according to claim 6.
8.  A battery module comprising the lithium secondary battery according to claim 7 as a unit cell.
9.  Power storage device comprising a battery module according to claim 8.

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